Twelve genes in the 11q23q25 band region of chromosome 11 were found amplified in a patient with acute myelogenous leukemia. They include five genes important in T-cell receptor and antigen recognition (CD3 epsilon, delta and gamma, N-CAM and Thy-1) and the proto-oncogene ets-1. The order of genes in this region was determined using pulse field electrophoresis and Southern blots of somatic cell hybrids, each containing a single human derivative chromosome having an 11q23 breakpoint from six different chromosomal defects. A common breakpoint region was found between the 11q23.3 CD3 gamma and ets-1 genes in four recurrent genomic rearrangements found in acute monocytic (AMoL) and myelomonocytic leukemia (AMMoL), acute lymphocytic leukemia (ALL) and B-cell diffuse lymphoma, using somatic cell hybrids. Utilizing a lambda genomic library of a B-cell lymphoma cell line with a t(11;14) (q23.3;q32.3), we have found evidence that the IgH gene C gamma 2 of chromosome 14 is rearranged with chromosome 11 specific DNA. The involvement of the 14q32.3-IgH region, which has been the subject of extensive molecular analysis, should facilitate the cloning and sequencing of a putative oncogene involved in the 11q23.3 breakpoint. This would aid in determining whether the same or a different region of the putative oncogene is involved in similar translocations found in other patients with diffuse lymphoma. Transcription and exon sequences of the gene in question will be studied by Northern blot analysis and cDNA libraries. Selected cDNA clones will be used to map introns and exons of the genomic clones and define the boundary of the gene S1 nuclease digestion. Probes generated from genomic and cDNA libraries from t(11;14) positive diffuse lymphoma will be used in Southern and Northern blots to find out whether the 11q23.3 gene is involved in any of 15 additional recurrent rearrangements of band 11q23 (with a chromosome other than 14) found in subgroups of All, CLL, AMoL, AMMoL and preleukemia. If the same putative 11q23 oncogene is involved, somatic cell hybrids from a t(4;11) (q21;q23.3) from two patients with ALL, a t(9;11) (p.22:q23.3) from one patient with AMoL, an inv ins(X;11) (q24;q23q21) from a patient with AMMoL and a CLL del(11) (q14q23), will be used to construct genomic libraries to characterize, in the reciprocal chromosome breakpoint 4q21, 9p22, Xq24 and 11q14, genes that may help explain the different cell phenotypes observed, since such genes may play a role in stem cell differentiation toward pre-B, B, monocytic or myelomonocytic cell lineage.